The Virtual Photonics Technologies (VPT) Core within LAMMP was newly established in 2008 with a multipronged mission to (a) develop state-of-the-art computational algorithms for simulation and analysis of biophotonic signals; (b) assemble these computational tools within a modular and extensible open-source software platform known as the Virtual Tissue Simulator (VTS); and (c) deploy and disseminate these computational tools to the Biomedical community through command-line interfaces, graphical user interface (GUI) operated software, and educational resources including workshops. The focus of VPT for this funding cycle is to initiate and develop three important modeling and computation topics that span microscopic to macroscopic spatial scales and address current emerging needs and challenges in Biophotonics. For each of these topics, we will pursue not only algorithm development but also integration into the VTS. This will facilitate multiple pathways for deployment and dissemination including support via online documentation, web logs, and live educational workshops. Our specific aims focus on development, implementation, and dissemination of; I: Huygens-Fresnel Electric-field Monte Carlo (HF-EMC) methods for model-based microscopy in deterministic cellular and tissue structures II: Nth-order Spherical Harmonic Expansion with Fourier decomposition (SHEFn) for radiative transport modeling, measurement design, and inverse problem solving on mesoscopic/macroscopic spatial scales III: Monte Carlo methods using Adaptive Density Estimation (MCADE) for real-time simulations of radiative transport in 3D heterogeneous tissue systems In each of these research thrusts we have formed partnerships, either within LAMMP or externally, to apply and test these methods during their development, to ensure their accuracy, ease-of-use, utility, anci suitability for Biomedical applications. Such partnerships are essential to accelerate and optimize the development and delivery of novel modeling and computational methods.